This invention relates to apparatus for introducing particulate material into a vessel or chamber that contains gas at a pressure substantially different from atmospheric pressure, and more particularly to such apparatus comprising gas valve means adapted to be moved to open and close at appropriate times to permit flow of particulate material into the vessel while minimizing gas pressure charge from such vessel during the charging operation.
Such a vessel may have an internal gas pressure above or below the pressure of ambient atmospheric air; for convenience such vessel will be referred to hereinafter as a "pressurized" vessel.
Known apparatus often used for charging particulate material into pressurized vessels comprises a gas lock chamber separated from the pressurized vessel by gas valve means at the discharge end of the chamber between the interior of the chamber and the interior of the vessel, and having other gas valve means at the feed end of the chamber between the interior of the chamber and means supplying particulate material, such combination constituting a gas lock.
After the gas valve means at the feed end of the lock chamber is opened and while the gas valve means at the discharge end of the chamber is closed, particulate material is introduced into the chamber; by thereafter causing the gas valve means at the feed end of the lock chamber to be closed and the gas valve means at the discharge end of the lock chamber to be opened, the particulate material is passed from the chamber into the pressurized vessel. Thus, introduction of particulate material into the pressurized vessel can be effected with little if any change of gas pressure in the pressurized vessel particularly if the pressure of gas in the lock chamber is appropriately equalized with that in the vessel after the valve means at the feed end of the lock chamber is closed and before the valve means between the lock chamber and the pressurized vessel is opened.
If, as has often heretofore occurred, the particulate material passing through the gas lock means contacts the sealing surface of the gas valve means as by adhering to such surfaces or otherwise being interposed between them, proper sealing cannot be effected and gas leakage and undesired pressure variations can result.
Moreover, it often happens that particulate material that has been introduced into a lock chamber rises to a level in the chamber where it can impair proper closing movement and sealing of the gas valve means at the feed end of the chamber, so that the gas valve means cannot close and seal sufficiently to prevent undesired passage of gas and changes in gas pressure in the pressurized vessel and elsewhere. Similar problems can occur at the gas valve means at the discharge end of the gas lock chamber.
The possibilities of such problems arising from improper sealing are increased if automatic means are provided to control the operation of the valve means, because such improper closing and sealing of the gas valve means can impair proper automatic operation, particularly at high rates of handling large volumes of particulate material.
However, it is often desired to automatically control operation of apparatus embodying a gas lock chamber for introducing particulate material into a pressurized chamber, as in high volume high rate operations.